We’re happy to announce the 3rd edition of the Workshop on Open Citations and Open Scholarly Metadata (WOOC2022), to be held online on 5 October 2022 (h. 15-18 CEST).
It has now been two years since the last edition of the Workshop on Open Citations and Open Scholarly Metadata (WOOC2020) took place as an online event. During that event, the virtual format did not constrain an enriching and stimulating debate, fostered by the distinguished voices of the speakers involved.
In the past two years, the Open Science ecosystem has been enriched by growing infrastructures, new projects, and the increasing availability of open scholarly data. OpenCitations itself is now hosting over 1.36 billion open citations. We would like WOOC2022 to re-create a theme-focused virtual space to share updates, thresholds and challenges. Like the last event, WOOC2022 will take the form of a three-hour webinar for researchers, scholarly publishers, funders, policy makers, and opening citations advocates, interested in the creation, reuse, and improvement, of open citation data and open scholarly metadata, with speaker contributions followed by Q&A sessions. The workshop is organized around the following topics:
Reforming research assessment with open citations and open scholarly metadata;
Artificial intelligence to support the extraction and analysis of citations and metadata;
Sustainability of open science infrastructures;
Availability of open citations and open scholarly metadata in scholarly disciplines.
Participation
The participation is free of charge and requires no registration. The event will be live-streamed on OpenCitations YouTube channel and it will be possible to interact with the speakers through the YouTube live comments section during the streaming.
Program
During the Workshop on Open Citations and Open Scholarly Metadata, the talks of the distinguished speakers will be divided into four sessions, with one 5-minute break. At the beginning of the Workshop, OpenCitations director Silvio Peroni will acknowledge the selected author’s video contributions, whose links will be made available on the workshop website for engaging with interested parties and encouraging a broader discussion.
15:10 – 15.30 Victoria Moody: Lift, shift and re-use: Repurposing open access in new ways: The possibility (and probable necessity) of ensuring the capability and sustainability of research infrastructure assets through the enhanced deployment of open science approaches, creating new pathways for established approaches and extending their impact.
15:30- 15:50 Alberto Martín-Martín: Managing the scholarly record
16:35- 16:55 Jennifer Lin and Ana-Maria Istrate: Essential frontiers: open data & software citations, an automated ML approach
16:55- 17:15 Philipp Mayr: Handling Non-source items in the project OUTCITE
Session IV
17:15- 17:35 Chiara Di Giambattista: Where were we? The role of the community in the present and future of OpenCitations
17:35-17:55 John Chodacki
17:55- 18:00 David Shotton: Roundup discussion and conclusion
Visit https://workshop-oc.github.io/ to read the talks’ abstracts and find more information about the Workshop on Open Citations and Open Scholarly Metadata.
All the workshop materials will be made available at
In the scholarly ecosystem, a bibliographic citation is a conceptual directional link from a citing entity to a cited entity, used to acknowledge or ascribe credit for the contribution made by the author(s) of the cited entity. Citations are one of the core elements of scholarly communication. They enable the integration of our independent research endeavours into a global graph of relationships that can be used, for instance, to analyse how scholarly knowledge develops over time, assess scholars’ influence, and make wise decisions about research investment.
A copyrighted fact
However, as citation data, i.e. pieces of factual information aiming at identifying entities and relationships among them, are of great value to the scholarly community, it has been a “scandal” that they have not been recognised as part of the commons. Indeed, only recently we have seen some efforts – such as the Initiative for Open Citations (I4OC) – that have tried to change the behind-the-paywall status quo enforced by the companies controlling the major citation indexes used worldwide, convincing scholarly publishers to support the unrestricted availability of scholarly citation data by publishing them in suitable open infrastructures, such as Crossref and DataCite.
Of course, as for many other kinds of data, putting bibliographic and citation data behind a paywall is a thread to enabling the full reproducibility of research studies based on them (e.g. in bibliometrics, scientometrics, and science of science domains), even when such studies are published in open access articles. For instance, the results of a recent open access article published on Digital Scholarship in the Humanities, which aimed to analyse the citation behaviour of Digital Humanities (DH) research across different proprietary and open citation databases, are not fully reproducible since the majority of the databases used – namely Scopus, Web of Science, and Dimensions – do not make their bibliographic and citation data openly available.
In addition, the coverage of publications and related citations in specific disciplines, particularly those within the Social Sciences and the Humanities (SSH), is inadequatecompared tootherfields. Usually, this is due to the limited availability of born-digital publications accompanied by a wide variety of publication languages, publication types (e.g. monographs), and complex referencing practices that may limit their automatic processing and citation extraction. As a side effect, such a partial coverage may result in a considerable bias when analysing SSH disciplines compared to STEM disciplines that usually have better coverage in existing citation databases.
Reforming research assessment
All these scenarios have at least another negative effect on the area strictly concerned with the research assessment, which often uses quantitative metrics based on citation data to evaluate articles, people, and institutions. Indeed, the unavailability and partial coverage of bibliographic and citation data create an artificial barrier to the transparency of the processes used to decide the careers of scholars in terms of research, funding, and promotions.
to be open and transparent by providing machine-readable, unrestricted and reusable data and methods for calculating the metrics used in research assessment exercises, and
to leave to the research community, instead of commercial players, the control and ownership of the crucial infrastructures and tools used to retrieve, use and analyse such data within research assessment systems.
Thus, the leading guideline that can be abstracted is to follow Open Science practices even when assessing research and not only when performing research.
Some initiatives pushing for reforming the principles behind research assessment systems.
Introducing OpenCitations
Within this context, OpenCitations (full disclosure: I am one of its directors) plays an important role, acting as a key infrastructure component for global Open Science, and pushes for actively involving universities, scholarly libraries and publishers, infrastructures, governments and international organisations, research funders, developers, academic policy-makers, independent scholars and ordinary citizens. The mission of OpenCitations is to harvest and openly publish accurate and comprehensive metadata describing the world’s academic publications and the scholarly citations that link them, with the greatest possible global coverage and subject scope, encompassing both traditional and non-traditional publications, and with a breadth and depth that surpasses existing sources of such metadata, while maintaining the highest standards of accuracy and accompanying all its records with rich provenance information, and providing this information, both in human-readable form and in interoperable machine-readable Linked Open Data formats, under open licenses at zero cost and without restriction for third-party analysis and re-use.
For OpenCitations, open is the crucial value and the final purpose. It is the distinctive mark and founding principle that everything OpenCitations provide – data, services and software – is open and free and will always remain so. OpenCitations fully espouses the aims and vision of the UNESCO Recommendations on Open Science, complies with the FAIR data principles, and promotes and practises the Initiative for Open Citations recommendation that citation data, in particular, should be Structured, Separable, and Open.
The most important collection of such open citation data is COCI, the OpenCitations Index of Crossref open DOI-to-DOI citations. The last release, dated August 2022, contains more than 1.36 billion citation links between more than 75 million bibliographic entities that can be accessed programmatically using its REST API, queried via the related SPARQL endpoint, and downloaded in full as dumps in different formats (CSV, JSON, and RDF).
Collaborations between OpenCitations and other Open Science infrastructures and services.
In addition to the publication of citation data, a considerable effort has been dedicated to collaborating with other Open Science infrastructures working in the scholarly ecosystem, as summarised in the figure above. Since 2020, OpenCitations has significantly benefited from the scholarly community that resulted from the 2019 selection by the Global Sustainability Coalition for Open Science Services (SCOSS) of OpenCitations as a scholarly infrastructure worthy of financial support. The community funding permitted the appointments of people dedicated to the administration, communication, community development, and maintenance and improvement of the OpenCitations software and the computational infrastructure on which it runs. In addition, OpenCitations started its involvement with OpenAIRE and the European Open Science Cloud (EOSC), and it is collaborating with other funded projects project such as RISIS2, OutCite, OPTIMETA and B!SON.
While OpenCitations is currently providing a good set of citation data, which is already approaching parity with other commercial citation databases and that has already been used in a few studies for research purposes, there is still a margin for improvement. Currently, the citations included in the OpenCitations Indexes come mainly from Crossref data, one of the biggest open reference providers. However, Crossref does not cover all the publishers of DOI-based resources. Indeed, other DOI providers, in some cases, expose citation relations in their metadata, such as DataCite. In addition, DOI-based publications represent just a limited set of all the bibliographic entities published in the scholarly ecosystem. Other identifier schemas have been used to identify bibliographic entities – and, for some publications, there not exist identifiers at all!
Thus, to address these two issues, OpenCitations is working on expanding its coverage according to two different directions. On the one hand, OpenCitations is developing two new citation indexes of open references based on the holdings of DataCite and the National Institute of Health Open Citation Collection, which, together with COCI, will be cross-searchable through the Unifying OpenCitations REST API.
On the other hand, OpenCitations has started working to create a new database entitled OpenCitations Meta, which will provide three major benefits. First, it will permit storing in-house bibliographic metadata for the citing and cited entities involved in all OpenCitations Indexes, including author identifiers using ORCID and VIAF identifier schemes where available. Second, it will provide better query performance than the present API system, which obtains bibliographic metadata on-the-fly by live API calls to external services, such as Crossref and DataCite APIs. Finally, it will permit indexing citations involving entities lacking DOIs, by providing them OpenCitations Meta Identifiers.
This last collection, combined with automatic tools for citation extraction from digital formats, is crucial for increasing the coverage of underrepresented disciplines and fields in bibliographic databases, such as SSH publications. One of the OpenCitations’ goals is to reduce this gap in citation coverage by setting up crowdsourcing workflows for ingesting missing citation data from the scholarly community (e.g. libraries and publishers). In the future, another contribution will be to set up tools for automatic extraction of citations that can also support small and local publishers, crucial assets for SSH research, that may find difficulties in carrying out citation extraction tasks on their own since using and maintaining a tool (or paying a company addressing those tasks on behalf of the publisher) requires extra costs beyond publishers’ finances.
To conclude: OpenCitations is one piece of a puzzle that is working to change existing scholarly practices to create an open and inclusive future for science and research in which the scholarly community owns and is responsible for its own data.
Since its inauguration in 2010, OpenCitations has always granted free access to its services to users throughout the world, with no requirement for registration or sign-up. Programmatic access to OpenCitations data can be obtained either via our SPARQL endpoints and our REST APIs. In addition, OpenCitations data – available in CSV, Scholix, and RDF formats – can be downloaded from data dumps made periodically and stored on Figshare, so as to enable large-scale analyses using the whole content of the data sets, and also be obtained via our user-friendly text-based search and browsing interfaces.
One of OpenCitations’ priorities is (and will always be) to keep its data globally open and available at zero cost and without restriction for third-party analysis and re-use. As a matter of sustainability, OpenCitations relies on financial support from the scholarly community, which includes those institutions that use OpenCitations data. However, OpenCitations has not so far had in place a proper system to monitor its users, and the main evidence of the impact of OpenCitations in different academic fields and countries has been incompletely obtained from direct contacts with our members and donors across the world, our collaborations with international projects, and the interactions on our social platforms (Twitter and LinkedIn).
We would now like to institute a system that enables us to follow the usage and assess the impact of OpenCitations more reliably. For this purpose, we are now happy to announce the launch of the OpenCitations Access Token System for access to the OpenCitations data and services.
An OpenCitations Access Token is an opaque character string that anonymously identifies a unique user of the OpenCitations APIs. OpenCitations assigns an access token only if authorized to do so by each user, who can request a token by inserting his/her email address into the access form and clicking “Get token”. Upon submission of such a request, each user will automatically receive a personal access token by email. Users can save their personal access token and reuse it every time calling the APIs of OpenCitations, by passing it as a value for the key access-token in the header of each API call.
Obtaining and using an OpenCitations Access Token is thus easy. It only requires a simple form request, and then the insertion of your personal token into the API call header when using OpenCitations REST APIs. OpenCitations will not store users’ email addresses or any personal information, so that the users’ privacy will be totally safeguarded. The token system just provides a simple mechanism for identifying unique users, for which the use of IP addresses is insufficient.
Obtaining an OpenCitations Access Token will take the user only a few seconds and needs to happen only once. You can request your OpenCitations Access Token here:
Use of an OpenCitations Access Token is not compulsory. However, token use will help OpenCitations incredibly, by enabling us to monitor the number of the unique users accessing our data and services, providing objective anonymized evidence of the number of institutions and researchers accessing our data either occasionally or on a regular basis, which we can then employ to demonstrate the usefulness of OpenCitations in the research environment. While the token system will initially be employed just for API calls (the most used service we offer), it will subsequently be extended to our other forms of data access.
OpenCitations exists for the people that use its data for research purposes every day, and thanks to their support. This is why obtaining precise knowledge of how many researchers and institutions are accessing our services is essential to us, since it will enable us to present the uniqueness and value of OpenCitations to new communities of stakeholders, and thus to make it possible to enlarge the already enthusiastic and diverse group of people and institutions supporting and using our Open Science Infrastructure.
To summarize: Getting and using an OpenCitations Access Token is voluntary, easy, and does not cost you anything. However, it will help OpenCitations a great deal. Please get your own token now, and use it next time you access OpenCitations. Thank you very much!
We announce the August 2022 release of COCI, the OpenCitations Index of Crossref open DOI-to-DOI citations, which is based on open references to works with DOIs within the Crossref dump dated August 2022. This new release extends COCI with more than 48 million additional citations, giving a total number of more than 1.36 billion DOI-to-DOI citation links.
This release includes citations from the articles published over the last four years by IEEE, whose bibliographic references were opened in June 2022.
A fundamental role in pushing the commercial publishers to open their citation data was played by Crossref’s recent announcement to change its reference distribution policy, by making all its metadata open.
Besides IEEE, COCI already includes the citation data derived from Elsevier (open via Crossref since December 2020) and from the last articles published by the American Chemical Society (whose references were opened in February 2021)
You can find more information about COCI in our open-access article
Ivan Heibi, Silvio Peroni & David Shotton (2019). Software review: COCI, the OpenCitations Index of Crossref open DOI-to-DOI citations. Scientometrics, 121 (2): 1213-1228. DOI: https://doi.org/10.1007/s11192-019-03217-6
Finally, just a reminder that the bibliographic and citation data in COCI:
can be queried using the OpenCitations Indexes SPARQL endpoint;
Posted on August 10th 2022 by Chiara Di Giambattista
More than a year ago, Ginny Hendricks, Director of Member & Community Outreach for Crossref, and a valued member of the OpenCitations International Advisory Board, published on the Crossref blog the post “The road ahead: our strategy through 2025”. In order to describe all Crossref’s principles and activities, Ginny presented the Crossref strategic planning framework as a diagram summarizing Crossref’s statements, key messages and truths. The clarity and immediacy of the diagram were such that we adapted it to present OpenCitations’ own statements and goals. The resulting poster “OpenCitations – what does the future hold?” was presented by our Director David Shotton at the OASPA2021 conference, and can be found in this blog post.
Although the poster offered a wide overview of OpenCitations values, unique traits, benefits and plans, it differed slightly from Ginny’s original diagram, in particular because it lacked a “Mission Statement”, scattering the relevant information within the “Values” and “Principles” boxes. Indeed, at that time (September 2021), we didn’t have a clearly defined Mission Statement.
Nevertheless, the creation of that poster was crucial in helping us start to articulate more clearly the purpose and meaning of OpenCitations. As David underlined in his post “From little acorns…a retrospective on OpenCitations”, since 2018 OpenCitations activities have progressively increased and, with them, the number of related journal articles, conference papers and technical definitions. OpenCitations’ involvement in international networks and collaborations (such as SCOSS and the OpenAIRE-Nexus project), together with our need of identifying and reaching out to new stakeholders to assure OpenCitations’ development and sustainability, has made it necessary to publicly define OpenCitations’ mission, unique strengths and next developmental steps.
After numerous revisions, aided by wise advice from members of the OpenCitations Advisory Board members, we’re now happy to publish the following three OpenCitations documents:
which together provide a summary of why we exist and where we are heading.
We are particularly proud of the definition of OpenCitations’ primary mission, namely
“to harvest and openly publish accurate and comprehensive metadata describing the world’s academic publications and the scholarly citations that link them, and to preserve ongoing access to this information by secure archiving.”
The Mission Statement also presents brief descriptions of the OpenCitations context, our vision, our value proposition and our relationship with the community and stakeholders.
The Uniqueness of OpenCitations provides the answer to the question ‘Why choose to use OpenCitations?’, and is a detailed presentation of OpenCitations’ benefits.
OpenCitations – Present Status and Future Plans summarizes OpenCitations’ ongoing activities, that can be quickly visualized on our public roadmap. It also introduces the OpenCitations Working Groups, served by the members of the OpenCitations International Advisory Board, which are currently working on the themes of governance evolution and community building, with the common purpose of driving OpenCitations along the path from being a ‘sustainable infrastructure’ (in POSI terms) to being an enduring community led andfinancially sustained infrastructure.
In fulfilling our mission and reaching our goals, the support and vital interest of our community members is fundamental. We request that you, as a member of our community, provide us with feedback on these documents and the ideas they contain, or indeed to ask for clarifications, to help us improving our mission and our communications to explain it. You can reach us here: contact@opencitations.net.
In March, The Global Sustainability Coalition for Open Science Services (SCOSS) celebrated, together with the generous funders and the projects involved (including OpenCitations), the achievement of an amazing milestone: a total of 4 million Euros raised so far for supporting the growth and development of Open Science Infrastructures. This significant sum is not just a number, but a concrete sign of the commitment of numerous institutions all over the world to ensure the success of vital organs of the Open Science ecosystem. Thanks to the pledges recently made, the new infrastructures selected for the third SCOSS pledging round have now started developing their services and can now look to the future with more surety.
At the end of 2019, OpenCitations was selected by SCOSS for its second pledging round, and since then much progress has been made. As the OpenCitations’ founder and director David Shotton recently stated:
“OpenCitations is growing, thanks to the generous support from our members and donors, and we thank SCOSS sincerely for bringing us into contact with them. The citation coverage provided by OpenCitations is now approaching parity with that of the leading commercial citation indexes, and our ambition, within the next five years, is for OpenCitations to be routinely used by our worldwide stakeholders as their primary source of comprehensive scholarly citation information”.
In 2020, OpenCitations monitored the achievements of the first year of SCOSS support and shared the most important updates in a blog post. After a review from SCOSS Advisory Group and the SCOSS Board, the OpenCitations 2021 report to SCOSS is now available in the SCOSS May newsletter. We’re proud of the successful developments that 2021 brought with it in many areas, from the technical enhancements to OpenCitations to its new supporters and partnerships.
After a two-year-long collaboration, we in OpenCitations recognise that one of the most precious benefits of being part of SCOSS is working within a community: SCOSS not only provides a framework but also a real family of supportive institutions that support the Infrastructures during their growth and provide a safety net if troubles occur along the path. The bi-monthly meetings organized by the SCOSS team enable dialogue with the other infrastructures within the same pledging round, while presentation and promotion to the institutions worldwide are fostered by participation in webinars and conferences. During 2021, OpenCitations participated in 16 events, and in 5 of them (LIBER Webinar 2021, JISC Webinar 2021, LIBER Annual Conference 2021, Open Science Fair 2021, and Open Access Tage 2021) OpenCitations’ director Silvio Peroni gave talks together with the representatives of others infrastructures involved in the SCOSS second pledging round.
In compliance with the POSI principles, SCOSS encouraged OpenCitations to set up an open governance structure. As described here, the organizational bodies included in the OpenCitations present governance are three: the Directors, the International Advisory Board, and the Council. Although executive power is still currently vested in the hands of the Directors, in the last two years the OpenCitations International Advisory Board, a committee that now comprises nine Open Science experts from different professional and academic backgrounds, has had a crucial role in guiding the OpenCitations activities, and it is now working on strategic developments in terms of collaborations, policies, support and governance. Moreover, last December OpenCitations organized a Webinar in conjunction with its Annual Meeting to present and discuss with the OpenCitations Council members OpenCitations’ recent developments and future plans.
OpenCitations is highly reliant upon the connections we have created and on people working together: thanks to the support we received throughout the last two years, the OpenCitations team has grown and now includes six people employed by the Research Centre for Open Scholarly Metadata at the University of Bologna, the administrative body for OpenCitations. Besides the previously announced appointments of Claudio Fabbri (Research Manager), Chiara Di Giambattista (Communications Director and Community Development Manager), Giuseppe Grieco (Software and Systems Developer), and Arcangelo Massari (Software Developer, working within the OpenAIRE-Nexus project), early in 2022 Ivan Heibi, Ph.D. candidate at the University of Bologna, joined OpenCitations with responsibility for the technical infrastructure, and Arianna Moretti, who recently graduated in Digital Humanities and Digital Knowledge, joined as a software developer. This enlarged team, involving young and motivated researchers, is working on numerous projects to be announced later in 2022. You can learn more about OpenCitations’ ongoing activities on our public roadmap.
OpenCitations’ aim continues to be the publication of open data describing the bibliographic citations linking global scholarly publications, with depth and scope, while maintaining the highest standards of accuracy and provenance. Most importantly, OpenCitations services will always be free, making global scholarly citation data available at zero cost and without restriction for third party analysis and re-use.
With its support, SCOSS has been helping OpenCitations to pursue its mission and spread the benefits of Open Science. However, 2022 will be the last year of the three-year-long support ensured by SCOSS. OpenCitations activities won’t stop in 2023 — indeed there still are many long-planned activities that we hope to initiate in the near future, given sufficient resources. This is why OpenCitations requires ongoing support from the scholarly community. All the information you may require to start helping us financially is available on the OpenCitations website: https://opencitations.net/membership
By supporting OpenCitations, you will embrace and sustain the ideals and vision of Open Science, and you will help in creating a more open, democratic and fair knowledge environment.
Want to keep yourself updated about the ongoing activities of OpenCitations? We have now publicly released the OpenCitations Roadmap, available on Trello.com:
The OpenCitations Roadmap consists of a board fulfilled with colour-labelled cards which present the goals so far reached, the present projects and activities, and the future plans. By clicking on the cards, it is possible to visualize a description for each activity, the progress state, and who in the OpenCitations team is working on it.
The OpenCitations Roadmap covers all kinds of activities divided according to the scope, identified by the coloured labels, in particular:
light blue for the technical development, such as the development of the software for the creation of the new database OpenCitations Meta and of DOCI, the OpenCitations Index of DataCite open DOI-to-DOI citations, and the re-engineering of the infrastructure and the website;
green for the data model implementation;
yellow for the data development, such as the bi-monthly COCI releases;
purple for the events and outreach activities.
The cards also highlight the activities related to the two EC-funded projects OpenCitations is involved in, OpenAIRE Nexus (blue label) and RISIS2 (orange label). We thank the OpenAIRE team for the help and suggestions during the Roadmap review process.
The OpenCitations Roadmap is an open work in progress that will reflect the developments and growth of OpenCitations. At OpenCitations, we don’t want this Roadmap to be just an online ‘showcase’, but a room in which to share ideas and opinions. We invite you – the members of our community, our stakeholders, the other Open Science actors, researchers, and librarians, and anyone who is interested in OpenCitations activities – to add a comment or a question in the ‘Leave feedback‘ card. This will help us to better understand our strong and weak points, and to stay in touch with the needs and thoughts of the community.
In this way, supplementing the conventional communications channels of email and the social platforms (our blog, Twitter, LinkedIn), the OpenCitations Roadmap will become a new virtual place for dialogue, where you can directly contribute to improve OpenCitations.
The incentives for new OpenCitations innovative solutions
Two years ago, in their canonical 2020 QSS paper on OpenCitations, Silvio Peroni and David Shotton anticipated the creation of the new database, OpenCitations Meta, able to “offer a faster and richer service” by storing bibliographic metadata “in house”. Meta would “avoid duplication of data by efficiently permitting us to keep […] a single copy of the metadata for each of the bibliographic entities involved as citing or cited entities in the different OpenCitations’ citation indexes”, would remove the requirement for potentially slow API calls to external metadata sources such as Crossref and ORCID, and would enable us to index citations involving entities lacking DOIs.
Important synergies to achieve goals
Today, thanks to the recent involvement of OpenCitations in two EC-funded projects, the OpenAIRE-Nexus Project (Horizon 2020 EU funded project, GA: 101017452) and the RISIS2 Project (Horizon 2020 EU funded project, GA: 824091), the development of OpenCitations Meta has commenced, with a planned release date later in 2022.
The OpenAIRE-Nexus project started in January 2021 to embrace and expand the operation of a portfolio of thirteen services, provided by OpenAIRE infrastructure, public institutions, organisations and universities, classified into three portfolios entitled PUBLISH, MONITOR, and DISCOVER. The OpenAIRE-Nexus portfolios focus on the demands of the three main categories of the research lifecycle. Therefore, OpenAIRE-Nexus makes sure such services are integrated to provide a uniform Open Science Scholarly Communication package for the European Open Science Cloud (EOSC). Within the OpenAIRE Nexus project there is scope for producing not only support materials (factsheet, guides, video tutorials, demos) but also training sessions where the services in the three portfolios will be showcased, anticipating the EOSC onboarding process. The role of OpenCitations in the project is to provide open bibliographic citations, and interconnect and integrate (and vice versa) functionalities with the OpenAIRE Research Graph and more OpenAIRE-Nexus services such as EpiSciences, OpenAIRE MONITOR) the core component of OpenAIRE infrastructure and services and of the EOSC Resource Catalogue.
Additionally, we are happy to announce our recent involvement in the RISIS2 Project. The Research Infrastructure for Science and Innovation Policy Studies (RISIS) is a project funded by the European Union under a Horizon2020 Research and Innovation Programme. RISIS2 involves 18 partners working together to create and maintain a research infrastructure for the field of Science, Technology, and Industry (STI) Studies, and to build an advanced research community in this field. OpenCitations’ contributions to RISIS2 will include not only the creation of OpenCitations Meta but also the development of a new citation index of open references, the OpenCitations Index of DataCite Open Citations (DOCI), which will be based on the open reference holdings of DataCite and, together with COCI, will be cross-searchable through our unified OpenCitations API.
Lessons learnt so far
A year into the OpenAIRE-Nexus project, we have found that one of the most significant benefits for OpenCitations is our involvement with this wide cooperative network of European research infrastructures, services, and communities, within which we can exchange experiences, ideas, and knowledge, and discuss any challenges and outcomes with our colleagues. More importantly, OpenCitations becomes positioned within the Open Science ecosystem, as a valuable innovative infrastructure with strong proof of integration and interoperable operations. Being part of the OpenAIRE-Nexus team has opened up more future challenges and expectations, and raised the bar for the inclusion of more functionalities of value. Thanks to the dedication of its efficient communication team, OpenAIRE is also helping us by communicating OpenCitations services to additional users and stakeholders, by inclusion within the comprehensive OpenAIRE services catalogue, by releasing an OpenCitations factsheet and by permitting us to present the latest information on OpenCitations through established events (i.e. Open Science FAIR 2022). FAIR and openness of information is our motto, and we strongly promote this through all our activities.
Expanding our team
As announced in our previous blog post “Five reasons why 2021 has been a great year for OpenCitations”, the support we receive from the EU as part of OpenAIRE-Nexus has enabled our recent appointment of Arcangelo Massari, a software developer who is now playing a crucial role in the creation and development of OpenCitations Meta.
As the year 2022 progresses, we look forward to bringing you further information about other new goals for OpenCitations, made possible by the support we receive from our numerous partnerships.
2021 is just behind us. Since January is “the Monday of the months”, as F. Scott Fitzgerald once wrote[1], it’s a good time to take stock of what happened at OpenCitations during the past year.
Among the numerous events, achievements and challenges that 2021 brought with it, we want to highlight five milestones which make us proud to look back:
1. We extended our coverage to well over one billion citations
During 2021, OpenCitations’ largest index COCI (the OpenCitations Index of Crossref open DOI-to-DOI citations) was able to include for the first time the citation links involving references that had been opened at Crossref by Elsevier and the American Chemical Society, thereby greatly expanding its coverage. The last release of COCI (November 2021) is based on open references to works with DOIs within the Crossref dump dated October 2021, and, as a result, COCI now contains information on more than 1.23 billion citations involving almost 70 million publications. A recent analysis by Alberto Martìn-Martìn (Facultad de Comunicación y Documentación, Universidad de Granada, Spain), published on the OpenCitations Blog in October, shows that the citation coverage provided by OpenCitations is approaching parity with that of the leading commercial citation indexes, Web of Science and Scopus, offering a viable alternative upon which to base open and reproducible metrics of academic performance.
2. OpenCitations team grew
Last summer, we appointed Claudio Fabbri as our Administrator and Research Manager to take responsibility for the day-to-day administrative and financial activities of OpenCitations; Chiara Di Giambattista as Communications Director and Community Development Manager to take care of all communications and community interactions made on behalf of OpenCitations; and Giuseppe Grieco as our new Software and Systems Developer to take charge of technical development related to the OpenCitations services.
Thanks to the support from the OpenAIRE Nexus project, the team has also recently welcomed Arcangelo Massari as our new Software Developer to take care of the development of the new database OpenCitations Meta. We anticipate further appointments during 2022!
Our International Advisory Board met in November, and we thank its members for the valuable advice they provided. The Board will meet again later this month.
3. We participated in many international meetings
During the past year, OpenCitations’ directors Silvio Peroni and David Shotton took part in numerous international conferences, webinars and workshops, including the LIBER Annual Conference 2021, the OS Fair 2021, OASPA 2021 and FORCE2021. These provided excellent opportunities to describe and promote OpenCitations, to reach out to new potential stakeholders, and to discuss with other experts the main themes of our activities and plans as they relate to Open Science.
The year ended with a bang, with the announcement during the closing session of FORCE2021 that the 2021 Open Publishing Award for Open Data had been awarded to OpenCitations.
4. We received a world of support
In 2021, thanks to our involvement in the SCOSS funding campaign and to our commitment to reaching out to the libraries and universities potentially interested in OpenCitations, we gathereda wide international community of stakeholders and supporters around us. We are deeply thankful to the 6 consortia and 56 institutions across the globe which are now supporting us financially, thus making it possible for us to enhance our services and expand our team. You can find the full list of our supporters on the OpenCitations website and in this recent Thank You video:
Additionally, in January 2021, we started our involvement in the EC-funded OpenAIRE Nexus project, bringing us into closer collaboration with our European colleagues and infrastructures, including OpenAIRE. The main aim of the project is to create a framework of services for assisting in publishing research, monitoring its impact, helping promote its discovery, and integrating it into the European Open Science Cloud (EOSC) “for the benefit of the open science community worldwide”. In OpenCitations, we’re thrilled to be part of this collaborative project by providing open bibliographic citations as part of the open data components of OpenAIRE and the EOSC.
5. We set the stage for future developments
Thanks to the research grants and the support and endorsement we have received from the international scholarly community, we are now working on a variety of new services, thus setting our goals for the coming years. In particular, we want to enhance OpenCitations partnerships and dialogue with the scholarly community; to collaborate with colleagues to develop new services that will expand our citation coverage, including new OpenCitations indexes of NIH-OCC, of DataCite and of other sources of open references, that will all be searchable through a single API; and to create OpenCitations Meta, our new database that will hold comprehensive bibliographic metadata of the publications involved in our indexes citations, thereby enabling faster query responses and the ability to host citations involving publications lacking DOIs[2].
A few months ago, I was invited to have a talk at the European Computer Science Symposium on an aspect of my research I particularly care about, that of open citations. What I tried to address during the presentation concerned the current status of open citation availability in a particular domain, Informatics, by using two open datasets, i.e. DBLP for gathering bibliographic metadata about relevant publications and OpenCitations’ COCI for identifying citations where such publications are involved. This post briefly introduces the preliminaries and results obtained from the material used to prepare the talk.
Open citations and where to find them
A citation is a conceptual directional link between a citing entity and a cited entity which is defined by means of specific textual devices contained in the text of the citing entity, e.g. a bibliographic reference denoted by an in-text reference pointer (e.g. “[3]” or “(Doe et al, 2021)”). While reasons for citing may vary, citations are used in academia for acknowledging others’ work and enabling building trails of relations defining how science evolves in time.
The data needed to describe a citation should include, at least, a representation of such a conceptual link and the basic bibliographic metadata to identify the citing and cited entities, i.e. those typically used for defining bibliographic references such as authors’ names, year of publication, the title of the work, venue of publication, pages, identifiers, etc. We say that a citation is open when these citation data are in the public domain and can be retrieved freely (via the HTTP protocol) in a structured and machine-readable format (e.g. JSON or RDF) without accessing the source of citing article defining it, which, potentially, could be behind a paywall.
OpenCitations [full disclosure: I am one of its directors] is one of the founders of the Initiative for Open Citations (I4OC) and one of the open scholarly infrastructures providing open citation data through several channels (REST APIs, SPARQL endpoints, Web interfaces, full dumps in different formats). As of 31 December 2021, it makes available more than 1.2 billion open DOI-to-DOI citation links between more than 69.5 million bibliographic resources, which are mainly journal articles but also include books, book chapters, datasets, and other DOI-identified resources. The entities involved in such citations come from different domains, spanning from Medicine articles to Humanities publications, and have recently approached parity with those included in well-known proprietary services such as Web of Science and Scopus.
What about Informatics
Such a huge mass of open citations available enables us to analyse citation coverage in different scholarly disciplines, e.g. to understand which publishers contributed to the availability of open citation data in a discipline and to check what are the citation trails between different disciplines. However, to compute such citation coverage, we need to have some information that allows us to identify when a particular bibliographic resource involved in a citation belongs to the particular discipline we want to analyse. We can use information about the subject categories of publications (e.g. that of Web of Science), if included in citation indexes, to identify the discipline(s) of a given bibliographic resource. Unluckily, OpenCitations does not provide this information and, as such, we need to rely on external repositories for gathering subject categories of publications, e.g. collections of bibliographic metadata of disciplinary publications.
In the context of Informatics, there is at least one well-known resource gathering and exposing bibliographic metadata of a large part of Computer Science publications, i.e. DBLP. As of 30 December 2021, DBLP contains more than 5.9 million publications published in 1,781 journals and in the proceedings of 5,621 conferences, involving more than 2.9 million authors that are manually curated (and disambiguated) by the DBLP team.
DBLP can be used as a proxy to understand if a particular publication belongs to the Computer Science subject category. Through it, it is possible to understand how many citations in OpenCitations involve Computer Science publications by comparing the DOIs of citing and cited entities with those available in DBLP. In particular, using the OpenCitations’ COCI September 2021 dump and DBLP October dump, I found that more than 80 million citations in COCI involved at least one of the 4,637,865 entities in DBLP (considering only journal articles, conference proceedings papers, books and book chapters). As shown in Figure 1, only 39% of these citations are between citing and cited entities both included in DBLP, while the rest of them either come from or go to publications not listed in DBLP – that, potentially, could not be Computer Science publications.
Figure 1. A Venn diagram showing how many citations involving Computer Science publications (obtained from DBLP) are included in OpenCitations.
Additional information about the publishers of such DBLP entities, retrieved by querying the Crossref API and the DataCite API with entities’ DOIs, are shown in Table 1. IEEE is the publisher with the biggest number of entities of those considered for this study, and its entities are involved in more than 18.9 million incoming and 21.5 million outgoing citations. The other bigger publishers, in terms of entities and citations, are Springer, Elsevier, ACM and Wiley. It is worth mentioning that the two publishers responsible for publishing mainly Computer Science journals and a relatively low number of conference proceedings (if any), i.e. Elsevier and Wiley, are those providing the highest number of openly-available references per publication (on average, around 29 and 37 cited works for each publication respectively).
Publisher
DBLP entities
COCI incoming citations
COCI outgoing citations
IEEE
1,730,485
18,930,055
21,582,093
Springer
1,012,534
18,482,132
11,179,566
Elsevier
574,860
15,536,207
17,019,716
ACM
433,188
3,695,255
6,050,342
Wiley
89,662
3,350,183
3,357,065
Table 1. The DBLP entities retrieved in the study grouped by their publisher and their incoming and outgoing citations according to COCI.
Future developments
Of course, this study does not provide full coverage of open citations in Computer Science but just a preliminary insight. First, as anticipated below, DBLP does not have the complete coverage of all CS-related publications since there are some venues that are not listed there (yet). Thus, some relevant open citations could not be extracted from COCI if these involve as citing and cited entity non-DBLP publications that belong to the CS domain. However, it is worth mentioning that no bibliographic and citation database (including commercial and proprietary ones) has a full disciplinary coverage anyway and DBLP is, probably, the most comprehensive collection of Computer Science publications metadata (something that could be assessed in future analysis).
Along the same lines, the index of open citations used, i.e. COCI, does not contain all the citations defined in CS publications, but only DOI-to-DOI citations as retrievable from Crossref data. Although Crossref is the biggest DOI provider and it is used by the majority of the big publishers,citations defined in publications with a non-Crossref DOI (e.g. DataCite) and those not having any DOI assigned (e.g. the papers published in CEUR Workshop Proceedings) are not included in COCI and, consequently, have not been used in the analysis. However, OpenCitations plans to extend its data coverage adding more sources in the next years. Thus, it would be interesting to replicate the same analysis in the future to see if and how much the coverage increase, at least in the context of Computer Science publications.
Still about coverage, currently (i.e. 31 December 2021) the only publisher of those included in Table 1 which is not providing open references through Crossref is IEEE. Indeed, while COCI includes several citations involving IEEE publications as citing entities, there is no availability of such citation after October 2018, when IEEE decided not to allow anymore Crossref Metadata Plus users to access these reference data.
Finally, analysing the preliminary results of this study, it would be interesting to understand which are the main subject categories of non-DBLP publications included in the 61% of citations shown in Figure 1 (e.g. by using the Scimago Journal and Country Rank database to retrieve their subject categories) to understand what are the citation dynamics between Informatics and other disciplines. However, I will leave the answer to this question to future analysis.
A final remark on reproducibility
Since several of the suggestions provided above start from the idea of either replicating or extending this study with additional materials and insights, it is important that all data and software used to perform the analysis are available online to permit its reproducibility. To this end, I have published both the software and the data retrieved online with open licenses to enable anyone to reuse it freely for any purpose.
